ABSTRACT. The geographical position of the Byzantine Empire determined the importance of its maritime commerce. Constantinople played a central role in the communication and exchange network between the western Mediterranean, the Black Sea, and the Islamic Middle East. The capital always welcomed foreign merchant communities but, from the 12th century on, it suffered under the Italian domination that integrated the Byzantine Empire into the system of international trade, yet to the detriment of the indigenous traders and the imperial treasury. A partial revival of Byzantine trade under Italian control occurred in the 14th century.
RÉSUMÉ. La position géographique de l'empire byzantin détermine l'importance de son commerce maritime, Constantinople jouant un rôle central dans le réseau de communications et d'échanges entre la Méditerranée occidentale, la mer Noire et le Proche-Orient islamique. La capitale a toujours accueilli des communautés marchandes étrangères, mais subit à partir du XIIe siècle la domination des Italiens qui intègrent l'empire byzantin dans le système du commerce international, mais au détriment des marchands indigènes et du trésor impérial. Un certain renouveau du commerce byzantin, sous l'égide des Italiens survient au XIVe siècle.
One of the foundations of the Byzantine economy and an important source of Byzantium's economic prosperity was trade. The geographic position of the Byzantine Empire, which was a state centered on the eastern Mediterranean, the Aegean, and the Black Sea, meant that maritime trade – both domestic and international– was of prime importance. Scholars agree that in the pre-modern era sea transport was considerably cheaper than moving commodities by land, from which it follows that maritime trade was more profitable than overland trade, despite the risks and dangers it might involve. The maritime character of the Byzantine Empire, therefore, played a crucial role in its economic development throughout its existence from the 4th to the 15th century. Despite unfavorable political circumstances, wars, and piracy that disrupted naval communications at various times, the sea always remained a major factor fostering trade and a generally flourishing economy in Byzantium.
Many port cities of the empire, including most notably Constantinople, Thessalonike, Trebizond, Attaleia, and Monemvasia, depended on the sea for their existence and owed their prosperity to their maritime communications.